1. Field of the Invention
This invention relates to a camera in which exposure is electrically and mechanically controllable.
2. Description of the Prior Art
Generally, there are two systems of controlling the shutter blades of a camera, i.e., electrical control by a construction including an electric circuit which requires power supply and mechanical control by a mechanical construction which does not require power supply. In a camera in which both of the above-described two exposure controls are possible, change-over between the mechanical control and the electrical control may be effected, for example, by a mechanical switch exclusively for change-over connected in series with a power source and operatively associated with a shutter dial for setting the shutter time. In the electrical control mode, when the shutter time has been set by the shutter dial, the circuit for the electrical exposure control is supplied with power by the mechanical switch and is operated thereby. On the other hand, in the mechanical control mode, when the shutter time has been set by the shutter dial, the mechanical switch changes over to thereby cut off the power supply to the circuit for the electrical exposure control and exposure is controlled by the mechanical exposure control construction.
However, there are problems such as the wear and tear or destruction of the mechanical switch connected in series with the power source as previously described which may result from the repeated use of the mechanical switch for a long time, and the complication of the construction which results from the mechanical switch being provided in the shutter dial.